The Lonely Computer was a short prose story published online on two pages. It totalled 3,055 words.
When trying to reach 1985 for a shopping trip, the TARDIS drags the Tenth Doctor and Donna off course by twelve hundred years, landing them in Belgium in the year 800. They arrive in a pantry used for storing vegetables and meat. Using his sonic screwdriver, the Doctor opens the only door available but is told to stop by two guards who take them into the kitchen. A man named Baldebert confronts them and declares the Doctor the Emperor's official food taster. Baldebert welcomes them to the court of Charlemagne. He lets the Doctor taste several dishes to see if they are poisoned. In the middle of testing, a young boy named Macon runs in, declaring that Charlemagne had disappeared. The Doctor becomes worried, because the Emperor had a meeting with the Pope later that day and if that meeting did not happen, Charlemagne would never have been crowned head of the Roman Empire. The Doctor and Donna follow Macon to where Charlemagne had disappeared. There the Doctor finds quantum detritus, left behind when someone or something has been taken out of time.
The Doctor and Donna disappear and find themselves in a long abandoned palace. A booming voice informs them that they are in the Palace of Hy-Ridion; the Doctor looks out the window. They are not on Earth. The voice introduces itself as Momus and says they are on Planet 12 of the Ridion Alliance. Momus says that the Doctor is the final guest in the Great Dinner Party, which Momus has spent a long time gathering. Momus himself is a small computer hovering in the air. A hidden door in the wall opens to reveal some of history's greatest leaders, artists and scientists (including Charlemagne) who are arguing and demanding that they be released. The Doctor has a talk with Momus, who says that after his planet's population of great scientists decreased after the Seven Hundred Year War, he decided to bring all of Earth's greatest minds to bring the planet to a new age. The Doctor reasons with Momus and persuades him to take the people home.
- Tenth Doctor
- Donna Noble
- Winston Churchill
- Noël Coward
- Francis Drake
- Joan of Arc
- I, Claudius is referenced by the Doctor.
- The depiction of Cleopatra is based on Elizabeth Taylor's portrayal of the character in Cleopatra.
- Donna thinks she recognises Galileo Galilei but his presence was not confirmed.
- The Fourth Doctor previously met Boudica in the company of Leela in Norfolk during her revolt against the occupying Roman forces in 60. (AUDIO: The Wrath of the Iceni)
- The Doctor would later recall walking through the forest with a bow and arrow in TV: The Unicorn and the Wasp.
- The Doctor and Winston Churchill would meet again in TV: Victory of the Daleks, after the Doctor began his next incarnation.
- The Doctor once told Donna that Cleopatra's beauty was greatly exaggerated. (PROSE: Ghosts of India)